Liquid Formualations

Question 1

What is a liquid formulation?

Answer 1

A homogenous one-phase system that contains the drug and the solvent

Question 2

How does low pH enhance solubility of a drug? (i.e. which form of drug dominates) Additionally what happens to the total solubility if a co-solvent is added

Answer 2

In Acidic Conditions (low pH) there is a higher conc. of protons - equilibrium shifts to the left - unionised form dominates
–> unionised forms have a greater ability to dissolve in non-polar solvents
- S(total) increases if alcohol Is added in this pH range

Question 3

How does intermediate pH affectt solubility of drug?

Answer 3

solubility values of both the ionised and unionised forms are comparable as the pH approaches the drugs pKa

Question 4

How does high pH enhance solubility of drug (i.e. which form of drug dominates) Additionally what happens to the total solubility if a co-solvent is added.

Answer 4

• IONISED FORM dominates
• S(total) decreases if alcohol is added

Question 5

What does inclusion of a co-solvent do?

Answer 5

It increases the solubility of the UNIONISED FORM

Question 6

Co-solvency affects the solubility of a drug. Define co-solvency.

Answer 6

A phenomenon where a co-solvent which is non-polar in nature is added to a primary solvent such as water to simply improve the solubility of a particular drug

Question 7

Give 2 specific examples of co-solvency

Answer 7

• Propylene glycol (co-solvent) dissolves co-trimoxazole in water
• Alcohol and syrup dissolves paracetamol in elixir

Question 8

Define dialectric constant of a solvent?

Answer 8

• inputted in ED discussion - still waiting for answer

Question 9

Does inclusion of a co-solvent increase or decrease DC

Answer 9

DECREASES!

Question 10

Does inclusion of water increase or decrease DC

Answer 10

INCREASES!

Question 11

How does micellar solubilisation affect solubiity of a drug

Answer 11

Micelles are made up of surfactants
When surfactant concentration is sufficiently high micelles are formed allowing drugs to be solubilised.
When it is low - they orientate towards the air-liquid interface

Question 12

What assumptions can we make if the solution is CLEAR?

Answer 12

All the drug has be dissolved and so the concentration of SURFACTANTS was optimal

Question 13

list 2 examples of surfactants and the types of drugs they dissolve

Answer 13

Polysorbates for fat-soluble vitamines and cetamacrogol for griseofulvin

Question 14

Outline the process of complexation to increase solubility

Answer 14

A drug [D] forms a complex [DC] with a complexing agent [C].

Question 15

List an example of a complexing agent and its type and 2 drugs that fits into it

Answer 15

Cyclodextrins:
There are 3 types - alpha, beta and gamma cyclodextrins which consists of 6, 7 and 8 units of glucose
DRUG NAME: mefenamic acid and meclofenamic acid

Question 16

List the basic steps in which liquid medications are made

List 2 considerations

Answer 16

1. API and additives solubilised in water
2. Flitration
3. Filling into containers

• Raw materials must meet requirements on microbial content
• Water must meet the regulatory requirement for purified water

Question 17

Function of preservatives?

Answer 17

If a microorganism randomly emerges in solution it inhibits its growth by killing It which in turn prevents spoilage and extends shelf life

Question 18

List a few examples of liquid preparations

Answer 18

1. Elixirs
2. Mixtures (either solution or suspension)
3. Linctus’s
4. Lotions
5. Liniments
6. Paints
7. Eye drops
8. Ear drops

Question 19

Define patient-centred care

Answer 19

Health services are tailored to people’s needs and provided in partnership with them. It also involves people, family and communities being respected, informed, engaged and adequately supported

Question 20

Define biomedical model of healthcare. Which diseases does it treat?

Answer 20

• Most dominant form of model in healthcare practise
• informs that a physical or mental illness in a person has a ‘cause’ which can be cured through treatment
  1. Identification of pathogenic stimulus
  2. Treatment
  3. Physiological changes
  4. recovery, chronicity or death
  Focuses on treating infectious diseases (e.g. influenza)

Question 21

Define biopschosocial model of healthcare
Outline the 3 factors and what diseases does it treat

Answer 21

Illness can be caused, treated, prevented by a combination of biological, psychological and social factors
1. Biological: genes
2. Psychological: beliefs, intelligence, mental health issues
3. Social: Education, financial stability, family support, access to healthcare services, public exercise equipment
Focuses on treating NCD’s (e.g. CVD, asthma and diabetes)

Question 22

Define open-ended questions

Answer 22

Allows the patient to provide a free-form long answer rather than a simple yes or no.
Should avoid ‘WHY’ questions

Question 23

Define close-ended questions

Answer 23

Directs a person to simply say a ‘yes’ or a ‘no

Question 24

Describe the elements involved in active listening

Answer 24

1. Taking quick notes while patient is talking about their situation
2. Double-check the information to reduce misunderstanding by repeating the information
3. Qualify the situation with questions
   - involves open body language and acknowledgement of concerns.

Question 25

Define empathy

Answer 25

Involves a non-judgemental and non-evaluative attitude towards the experience of others and acknowledgeing concerns (e.g I completely understand your frustration and I really appreciate your patience right now, thats ok we are all so busy these days)

Question 26

Surfactants of what HLB value are identified as a useful solubilising agnet

Answer 26

more than or equal to 15

Question 27

Whats one drawback of the beta-cyclodextrin

Answer 27

It is nephrotoxic

Question 28

Why do liquid formulations need to maintain a proper level of viscosity?
List 2 examples of viscosity enhancers

Answer 28

to enhancing pouring properties and palatability
- PVP
- Cellulose

Question 29

Why is density important and provide examples?

Answer 29

To avoid rise or fall in the cerebrospinal fluid
- dextrose

Question 30

Why is tonocity important and provide examples?

Answer 30

1. To avoid pain or irritation
   - NaCI
   - Mannitol